Titanium-containing waste liquid treatment method

Abstract

The invention provides a treatment method of titanium-containing waste liquid. The treatment method comprises the following steps: S1, pretreating the titanium-containing waste liquid to obtain a titanium-containing aqueous solution; determining the titanium content in the titanium-containing aqueous solution, wherein the titanium content is based on the mass percentage of titanium dioxide; s2, carrying out a neutralization reaction on the mixture to obtain a precipitate; the mixture comprises a titanium-containing aqueous solution, an alkaline substance and a seed crystal; the alkaline substance is used for controlling the pH value of a solution for neutralization reaction to be 5-8; the adding amount of the seed crystal is 0.1%-10%; and S3, carrying out post-treatment on the precipitate to obtain a titanium dioxide product. According to the method, titanium in the titanium-containing waste liquid can be effectively recycled, the resource utilization rate is increased, and resource utilization of waste is achieved; the titanium-containing waste liquid is converted into a titanium dioxide product, the quality of the titanium dioxide product is stable, and the granularity meets the requirement; moreover, the method is simple in process operation and relatively low in equipment requirement, and the treatment cost is reduced.

Description

Technical Field

[0001] The present invention relates to a method for resource treatment of titanium-containing waste liquid. Background Art

[0002] In industries such as petrochemical industry and catalyst production, for example, in the process of producing a series of high-efficiency polypropylene catalysts in the catalyst industry, a large amount of titanium-containing waste liquid will be generated. These waste liquids usually contain titanium compounds such as titanium tetrachloride and titanium (halogenated) alkoxide. If directly discharged, it will not only cause serious environmental pollution but also lead to waste of titanium resources.

[0003] Currently, the treatment methods for titanium-containing waste liquid mainly include harmless treatment means such as landfill and incineration, but these methods cannot effectively recycle titanium resources; there are also other titanium recovery methods, such as: cooling and filtering to separate titanium tetrachloride, or vacuum distillation to recover titanium tetrachloride; however, these methods have problems such as complex process, high cost, and unstable quality of the recovered products.

[0004] Therefore, there is an urgent need to develop a method for recovering waste titanium-containing waste liquid that is efficient, low-cost and can produce high-quality titanium dioxide products. Summary of the Invention

[0005] In order to overcome the defects of low resource utilization rate of titanium-containing waste liquid and complex recovery process in the prior art, the present invention provides a method for treating titanium-containing waste liquid. This method can effectively recover titanium in the titanium-containing waste liquid, improve the resource utilization rate, realize the resource utilization of waste, and has good environmental protection benefits; among them, the titanium-containing waste liquid is converted into titanium dioxide products with relatively high economic value, and the quality of the titanium dioxide products is stable and the particle size meets the requirements; moreover, the process operation of this method is simple, the equipment requirements are relatively low, and the treatment cost is reduced.

[0006] The present invention solves the above technical problems through the following technical solutions: The present invention provides a method for treating titanium-containing waste liquid, which comprises the following steps: S1. Pretreat the titanium-containing waste liquid to obtain a titanium-containing aqueous solution; determine the titanium content in the titanium-containing aqueous solution, and the titanium content is calculated as the mass percentage of titanium dioxide. S2. Carry out a neutralization reaction on the mixture to obtain a precipitate; the mixture includes the titanium-containing aqueous solution, an alkaline substance and a seed crystal; the alkaline substance is used to control the pH value of the solution in the neutralization reaction to be 5-8; the addition amount of the seed crystal is 0.1%-10%, and % refers to the mass percentage of the seed crystal in the mass of the titanium content. The seed crystal includes a titanium-containing solid powder, alumina, silica or a titanium-containing liquid solution; S3. Post-treat the precipitate to obtain a titanium dioxide product.

[0007] In step S1 of the present invention, "the titanium content is calculated based on the mass of titanium dioxide" can more accurately reflect the titanium content in the titanium-containing waste liquid; according to this titanium content, the addition amount of seeds in the subsequent process is determined.

[0008] In some embodiments, in step S1, the process of the pretreatment includes: separating oil and water from the titanium-containing waste liquid, and then performing solid-liquid separation.

[0009] In step S1 of the present invention, after the pretreatment, the obtained titanium-containing aqueous solution is a clear solution.

[0010] In some embodiments, in step S1, the titanium-containing waste liquid includes titanium tetrachloride and titanium alkoxide.

[0011] In some embodiments, in step S1, the titanium-containing waste liquid includes the waste liquid for producing polypropylene catalysts.

[0012] In some embodiments, in step S1, the titanium content of the titanium-containing waste liquid is 1% - 40%, and % refers to the percentage of the mass of titanium in the total mass of the titanium-containing waste liquid.

[0013] In a specific embodiment, the titanium content of the titanium-containing waste liquid is 5% - 15%, and % refers to the percentage of the mass of titanium in the total mass of the titanium-containing waste liquid.

[0014] In a certain embodiment, the titanium content of the titanium-containing waste liquid is 5% or 11%, and % refers to the percentage of the mass of titanium in the total mass of the titanium-containing waste liquid.

[0015] In some embodiments, in step S2, the titanium-containing solid powder includes: anatase, rutile or brookite.

[0016] In some embodiments, in step S2, the particle size of the titanium-containing solid powder is 20 - 50 nm.

[0017] In step S2 of the present invention, the alumina can be corundum, such as: α - Al2O3, γ - Al2O3.

[0018] In some embodiments, in step S2, the particle size of the alumina is 20 - 50 nm.

[0019] In step S2 of the present invention, the silica can be quartz.

[0020] In some embodiments, in step S2, the particle size of the silica is 20 - 50 nm.

[0021] In some embodiments, in step S2, the titanium-containing liquid solution includes: the liquid obtained by directly reacting the titanium-containing aqueous solution in step S1 with the basic substance. Herein, "direct reaction" means that the titanium-containing aqueous solution undergoes a neutralization reaction with the basic substance, and no seed crystal is added during this process.

[0022] In some embodiments, in step S2, when the seed crystal is a titanium-containing solid powder, alumina, or silica, the addition amount of the seed crystal is 0.1% - 2%, where % refers to the mass percentage of the seed crystal in the mass of the titanium content.

[0023] In some embodiments, in step S2, when the seed crystal is a titanium-containing liquid solution, the addition amount of the seed crystal is 1% - 10%, where % refers to the mass percentage of the seed crystal in the mass of the titanium content.

[0024] In some embodiments, in step S2, the timing of adding the seed crystal to the titanium-containing aqueous solution includes before the reaction, in the middle stage of the reaction, and in the late stage of the reaction, corresponding to the following conditions respectively: ① adding the seed crystal before adding the basic substance to the titanium-containing aqueous solution; ② adding the seed crystal when the reaction consumption of the basic substance reaches 1 / 2 after adding the basic substance to the titanium-containing aqueous solution (at this time the solution is green); ③ adding the seed crystal when the reaction consumption of the basic substance reaches 2 / 3 after adding the basic substance to the titanium-containing aqueous solution. The timing of adding the above-mentioned seed crystal will affect the size of the precipitate particle size, and thus affect the purity of the subsequent product; adding the seed crystal before or before the complete neutralization reaction can make the precipitate generated during the neutralization reaction of the basic substance more likely to adhere, and thus the precipitate particle size becomes larger, which is easier to filter during the post-treatment process, helping to improve the titanium recovery rate and product purity.

[0025] In some embodiments, in step S2, the basic substance includes sodium hydroxide or calcium hydroxide.

[0026] In some embodiments, in step S2, the basic substance includes a basic solution; the concentration of the basic solution is 10% - 30%, where % refers to the mass percentage of the solute in the basic solution in the mass of the basic solution.

[0027] In step S2 of the present invention, the basic substance is used to adjust the pH value of the mixture; therefore, those skilled in the art should know that the addition amount of the basic substance can be determined according to the pH value of the mixture.

[0028] In some embodiments, in step S2, when adding the basic substance to the titanium-containing aqueous solution, the temperature of the neutralization reaction is controlled at 50 - 80°C.

[0029] In some embodiments, in step S2, when adding an alkaline substance to the titanium-containing aqueous solution, the stirring speed is controlled at 100 - 300 r / min.

[0030] In some embodiments, in step S2, water is added to the titanium-containing aqueous solution, and the mass ratio of the added water to the mass of the titanium-containing aqueous solution is (2 - 5):1.

[0031] In a specific embodiment, after the step of adding water to the solution of the neutralization reaction is completed, the reaction continues for 30 - 40 min.

[0032] In step S2 of the present invention, when the pH value of the solution of the neutralization reaction is less than 4, the solution is strongly acidic, and it is difficult for titanium in the titanium-containing aqueous solution to be completely converted, resulting in a low titanium yield; when the pH value of the solution of the neutralization reaction is greater than 8, the alkaline substance will react excessively with the titanium-containing aqueous solution to generate impurities, affecting the product purity.

[0033] In some embodiments, in step S2, the pH value of the solution of the neutralization reaction is controlled to be 5.5 - 7.

[0034] In some embodiments, in step S3, the post-treatment process sequentially includes solid-liquid separation and drying and grinding.

[0035] In a specific embodiment, the solid-liquid separation includes steps of filtration or centrifugation.

[0036] In some embodiments, the treatment method of the titanium-containing waste liquid is carried out in a titanium-containing waste liquid treatment system; the titanium-containing waste liquid treatment system includes a pretreatment device, a neutralization reaction device, and a post-treatment device connected in sequence.

[0037] In a specific embodiment, the pretreatment device includes a filter and a composition analyzer.

[0038] In a specific embodiment, the neutralization reaction device includes a reaction kettle with a stirrer and a temperature control device.

[0039] In a specific embodiment, the post-treatment device includes a solid-liquid separation unit, a drying unit, and a grinding and classification unit; the solid-liquid separation unit includes a filter press or a centrifuge, and the grinding and classification unit includes a grinder and a classifier.

[0040] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0041] The reagents and raw materials used in the present invention are all commercially available.

[0042] The positive and progressive effects of the present invention are as follows: 1. Resource recycling and utilization: The present invention can effectively recover titanium resources from waste titanium-containing waste liquid, convert them into titanium dioxide products with high economic value, and improve the resource utilization rate.

[0043] 2. Simple process: The method of acid-base neutralization is adopted, the process operation is simple, the equipment requirements are relatively low, and the treatment cost is reduced.

[0044] 3. High product quality: By controlling the reaction conditions, titanium dioxide products with stable quality and particle size meeting the requirements can be produced, and the product purity of titanium dioxide can reach more than 95%.

[0045] 4. Remarkable environmental protection benefits: It reduces the pollution of waste titanium-containing waste liquid to the environment, realizes the resource utilization of waste, and has good environmental protection benefits. Detailed implementation manners

[0046] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. The experimental methods without specific conditions noted in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0047] Example 1 This example discloses a treatment system for titanium-containing waste liquid.

[0048] The treatment system for titanium-containing waste liquid includes a pretreatment device, a neutralization reaction device, and a post-treatment device connected in sequence; The pretreatment device includes a filter and a composition analyzer; The neutralization reaction device includes a reaction kettle with a stirrer and a temperature control device; The post-treatment device includes a solid-liquid separation unit, a drying unit, and a grinding and classification unit; the solid-liquid separation unit includes a filter press or a centrifuge, and the grinding and classification unit includes a grinder and a classifier.

[0049] Example 2 This example discloses a treatment method for titanium-containing waste liquid, which adopts the treatment system for titanium-containing waste liquid as in Example 1, and includes the following steps: Step S1. Pretreatment Collect 1000 L of waste titanium-containing waste liquid generated by an enterprise during the production of polypropylene catalyst, separate the oil phase through a separator, and remove the solid impurities therein with a filter to obtain a clarified titanium-containing aqueous solution; perform a composition analysis on the clarified waste liquid by chemical analysis methods. The titanium-containing waste liquid contains titanium tetrachloride and titanium alkoxide, and the measured titanium content is 11% (calculated as the mass percentage of titanium dioxide), and the waste liquid also contains a certain amount of impurities such as chlorine element.

[0050] Step S2. Acid-base neutralization reaction Transfer the above-mentioned clarified titanium-containing aqueous solution into a reaction kettle, add 3 times the amount of water for dilution, and then weigh 0.1% of the seed crystal (% is the mass percentage of the added amount of the seed crystal in the above titanium dioxide). The seed crystal is anatase solid powder with a particle size of 20 - 50 nm, and this seed crystal is added before the start of the neutralization reaction; Then slowly add a sodium hydroxide solution with a mass fraction of 10% to carry out a neutralization reaction, control the neutralization reaction temperature at 50 °C, and the stirring speed at 200 r / min. As the sodium hydroxide solution is added, white precipitates gradually form. When the pH value of the solution reaches 7, stop adding the sodium hydroxide solution and continue stirring the reaction for 30 minutes.

[0051] Step S3, Post-treatment Precipitate filtration: Separate the solid and liquid of the mixture after the neutralization reaction through a filter to obtain a titanium-containing substance precipitate; Drying and grinding: Dry with a drying device such as a muffle furnace for 2 hours, control the temperature at 80 - 150 °C; grind the obtained titanium dioxide product through a grinder to obtain a titanium dioxide product.

[0052] After testing, the titanium dioxide content of this product reaches more than 95%, meeting the relevant quality standards.

[0053] Example 3 This example discloses a method for treating titanium-containing waste liquid, which uses a titanium-containing waste liquid treatment system as in Example 1 and includes the following steps: Step S1, Pretreatment Collect 800 L of waste titanium-containing waste liquid generated by another catalyst production enterprise during the production of polypropylene catalysts. Separate the oil phase through a separator, conduct filtration and component analysis. The titanium-containing waste liquid contains titanium tetrachloride and titanium alkoxide, and the measured titanium content is 5% (calculated as the mass percentage of titanium dioxide), and the waste liquid also contains a certain amount of impurities such as chlorine element.

[0054] Step S2, Acid-base neutralization reaction Add 2 times the amount of water to the clarified titanium-containing waste liquid, and add calcium hydroxide emulsion with a concentration of 15%. When the reaction proceeds to the intermediate stage and the reaction consumption of calcium hydroxide reaches 1 / 2, at this time, it is observed that the solution turns green, and start to add 2% of silicon dioxide seed crystal (% is the mass percentage of the added amount of the seed crystal in the above titanium dioxide). The particle size of this seed crystal is 20 - 50 nm; control the reaction temperature at 70 °C and the stirring speed at 250 r / min. When the pH value of the solution reaches 6, stop adding the calcium hydroxide emulsion and continue stirring the reaction for 40 minutes.

[0055] Step S3, Post-treatment Precipitation washing: Separate the solid and liquid of the mixture after the neutralization reaction through a filter press to obtain a titanium-containing substance precipitate; Drying and grinding: Dry it in a muffle furnace for 2 hours with the temperature controlled at 80 - 150 °C; Grind the obtained titanium dioxide product through a grinder to obtain a titanium dioxide product.

[0056] After testing, the titanium dioxide content of this product reaches over 97%, meeting the relevant quality standards.

Claims

1. A method for treating titanium-containing waste liquid, characterized in that, It includes the following steps: S1. Pretreat the titanium-containing waste liquid to obtain a titanium-containing aqueous solution; determine the titanium content in the titanium-containing aqueous solution, and the titanium content is calculated as the mass percentage of titanium dioxide; S2. Carry out a neutralization reaction on the mixture to obtain a precipitate; the mixture includes the titanium-containing aqueous solution, an alkaline substance and seeds; the alkaline substance is used to control the pH value of the solution in the neutralization reaction to be 5-8; the addition amount of the seeds is 0.1%-10%, and % refers to the mass percentage of the seeds in the mass of the titanium content; The seeds include titanium-containing solid powder, alumina, silica or titanium-containing liquid solution; S3. Post-treat the precipitate to obtain a titanium dioxide product.

2. The treatment method of titanium-containing waste liquid according to claim 1, characterized in that, Step S1 satisfies one or more of the following conditions: ① The process of the pretreatment includes: carrying out oil-water separation on the titanium-containing waste liquid, and then carrying out solid-liquid separation; ② The titanium-containing waste liquid includes titanium tetrachloride and titanium alkoxide; ③ The titanium-containing waste liquid includes the waste liquid for producing polypropylene catalyst; ④ The titanium content of the titanium-containing waste liquid is 1% to 40%, and % refers to the percentage of the mass of titanium in the total mass of the titanium-containing waste liquid.

3. The treatment method of titanium-containing waste liquid according to claim 1, wherein, In step S2, the seeds satisfy one or more of the following conditions: ① The titanium-containing solid powder includes: anatase, rutile or brookite; ② The particle size of the titanium-containing solid powder is 20-50 nm; ③ The particle size of the alumina is 20-50 nm; ④ The particle size of the silica is 20-50 nm; ⑤ The titanium-containing liquid solution includes: the liquid obtained by directly reacting the titanium-containing aqueous solution in step S1 with the alkaline substance; ⑥ When the seeds are titanium-containing solid powder, alumina or silica, the addition amount of the seeds is 0.1%-2%, and % refers to the mass percentage of the seeds in the mass of the titanium content; ⑦ When the seeds are titanium-containing liquid solution, the addition amount of the seeds is 1%-10%, and % refers to the mass percentage of the seeds in the mass of the titanium content.

4. The treatment method of titanium-containing waste liquid according to claim 1, wherein, In step S2, the timing of adding the seeds to the titanium-containing aqueous solution satisfies one of the following conditions: ① Add the seeds before adding the alkaline substance to the titanium-containing aqueous solution; ② Add the seeds when the reaction consumption amount of the alkaline substance reaches 1 / 2 after adding the alkaline substance to the titanium-containing aqueous solution; ③ Add the seeds when the reaction consumption amount of the alkaline substance reaches 2 / 3 after adding the alkaline substance to the titanium-containing aqueous solution.

5. The treatment method of titanium-containing waste liquid according to claim 1, characterized in that, In step S2, the alkaline substance satisfies one or two of the following conditions: ① The alkaline substance includes sodium hydroxide or calcium hydroxide; ② The alkaline substance includes an alkaline solution; the concentration of the alkaline solution is 10%-30%, and % refers to the mass percentage of the solute in the alkaline solution in the alkaline solution.

6. The treatment method of titanium-containing waste liquid according to claim 1, characterized in that, Step S2 satisfies one or more of the following conditions: ① When adding the alkaline substance to the titanium-containing aqueous solution, control the temperature of the neutralization reaction to be 50-80°C; ② When adding the alkaline substance to the titanium-containing aqueous solution, control the stirring speed to be 100-300 r / min; ③ Add water to the titanium-containing aqueous solution, and the mass ratio of the added water to the mass of the titanium-containing aqueous solution is (2 - 5):1; ④ Control the pH value of the solution in the neutralization reaction to be 5.5 - 7.

7. The treatment method of titanium-containing waste liquid according to claim 6, characterized in that, After completing the step of adding water to the solution in the neutralization reaction, continue the reaction for 30 - 40 min.

8. The treatment method of titanium-containing waste liquid according to claim 1, wherein, In step S3, the post-treatment process sequentially includes solid-liquid separation and drying and grinding.

9. The treatment method of titanium-containing waste liquid according to any one of claims 1-8, characterized in that, The treatment method of the titanium-containing waste liquid is carried out in a titanium-containing waste liquid treatment system; The titanium-containing waste liquid treatment system includes a pretreatment device, a neutralization reaction device, and a post-treatment device connected in sequence.

10. The treatment method of titanium-containing waste liquid according to claim 9, characterized in that, The titanium-containing waste liquid treatment system satisfies one or more of the following conditions: ① The pretreatment device includes a filter and a composition analyzer; ② The neutralization reaction device includes a reaction kettle with a stirrer and a temperature control device; ③ The post-treatment device includes a solid-liquid separation unit, a drying unit, and a grinding and classification unit; the solid-liquid separation unit includes a filter press or a centrifuge, and the grinding and classification unit includes a grinder and a classifier.